Field of Invention
The present invention relates to an optical image capturing module, and more particularly to an optical image capturing module formed by four prisms, two wavelength-selective films to filter the specific light ray with different wavelengths, an alignment method for an upper substrate and a lower substrate, and an observation method for an upper substrate and a lower substrate using the optical image capturing module of the present invention.
Related Art
U.S. Pat. No. 3,684,384 discloses a compound optical prism module, which is formed with a truncated quadrangular, right prism with a 45° truncation and a rectangular prism united to the optical prism module to form a parallelepiped with a half-silvered mirror film at their interface and with a total reflecting mirror film at the vertical surface of the rectangular prism, so that the two components are opposed in their mated positions can be superposed in the same coordinate space for image observation. However, this prior art patent discloses the use of two right-angle prisms with different sizes, resulting in different lengths for an upper light path length and a lower light path length, limited manners of mounting light sources, and also a large module volume.
U.S. Pat. No. 5,519,535 also discloses a compound optical prism module, which is formed with two same size right-angle prisms and similar to U.S. Pat. No. 3,684,384. More particularly, a liquid crystal shutter is mounted onto one face of each right-angle prisms control image showing for objects at different sides, respectively. However, the liquid crystal shutter disclosed in this prior art patent sacrifices light intensity efficiency to some degree, and a number of control components are required.
U.S. Pat. No. 4,574,197 discloses a dual field of view sensing device, in which mainly a polygonal prism is used, and through mechanism rotation control, a light ray is refracted and then two parallel light paths are reflected into a single detector to obtain symmetrical light paths; switching of the light paths depends on the rotational position of the prism, and two different light beams are reflected into a single image space through the prism. However, the device volume disclosed in this prior art patent is too large, the light path is designed too long, and the mechanical control is too complicated.
In the prior art, to map two different images (or light beams) in a single image plane, different prism forms are mainly adopted, and the aforementioned prior art patents (U.S. Pat. No. 3,684,384 and U.S. Pat. No. 5,519,535) are the most common, in which a compound prism is used to reflect light paths from opposite image positions into a single image space. However, the problem that the reflection path lengths of the opposite light rays are not equal occurs in both patents. By taking image capturing into consideration, the working distance become unequal, causing that the opposite side objects must be placed at asymmetrical distances, which makes the fabrication process complicated. Also, currently a compound prism module has a number of refraction paths and a large volume, and no longer satisfied the current fabrication processes in the optoelectronics industry.
Therefore, an optical image capturing module having symmetrical light paths needs to be provided to solve the foregoing problem.